US11874159B2 - Ultrasonic sensor - Google Patents
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- US11874159B2 US11874159B2 US17/616,985 US202017616985A US11874159B2 US 11874159 B2 US11874159 B2 US 11874159B2 US 202017616985 A US202017616985 A US 202017616985A US 11874159 B2 US11874159 B2 US 11874159B2
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- matching layer
- piezoelectric element
- ultrasonic sensor
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Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H11/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties
- G01H11/06—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means
- G01H11/08—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means using piezoelectric devices
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R17/00—Piezoelectric transducers; Electrostrictive transducers
Definitions
- the present disclosure mainly relates to an ultrasonic sensor that transmits and receives ultrasonic waves.
- the difference in acoustic impedance (the product of the density of each substance and the speed of sound) between different substances is small, the ultrasonic waves propagates through an interface between the two substances, but if the difference in acoustic impedance is large, a ratio of the ultrasonic waves being reflected at the interface becomes higher than that of propagating. Therefore, as the difference in acoustic impedance decreases, energy is propagated with higher efficiency.
- piezoelectric elements used for ultrasonic sensors are generally made of ceramics (having a high density and a high acoustic velocity), and the density and the speed of sound in gas such as air in which the ultrasonic waves propagate are significantly smaller than those of ceramics. Therefore, the energy propagation efficiency from the piezoelectric element to the gas is significantly low.
- Z1 is an acoustic impedance of the piezoelectric element
- Z2 is an acoustic impedance of the acoustic matching layer
- Z3 is an acoustic impedance of the gas in which the ultrasonic waves propagate.
- an energy loss of the ultrasonic waves propagating through the acoustic matching layer needs to be suppressed low.
- a factor of the energy loss of the ultrasonic wave propagating inside the acoustic matching layer is that the acoustic matching layer is plastically deformed and the energy is dissipated as heat. Therefore, the substance used for the acoustic matching layer is required to be highly elastic.
- the acoustic impedance Z2 of the acoustic matching layer needs to reduce the acoustic impedance such that the acoustic impedance is brought close to the acoustic impedance Z3 of the gas.
- Substances exhibiting a low acoustic impedance mean that the speed of sound is low or the density is low, and in general, many such substances are easily deformed and are not suitable for the acoustic matching layer.
- the acoustic impedance of the solid piezoelectric element differs from the acoustic impedance of the gas by about five orders of magnitude, and in order to satisfy the formula (1), the acoustic impedance of the acoustic matching layer needs to be lowered to about three orders of magnitude of the acoustic impedance of the piezoelectric element.
- Z1 is an acoustic impedance of the piezoelectric element
- Z2 is an acoustic impedance of the first acoustic matching layer
- Z3 is an acoustic impedance of the second acoustic matching layer
- Z4 is an acoustic impedance of the gas.
- the second acoustic matching layer that makes ultrasonic waves propagate to the gas is desirably made of a very lightweight and hard material, and a foamed resin having relatively high elasticity has been used (see, for example, PTL 1).
- a resin material is used as a first acoustic matching layer and a foamed resin material is used as a second acoustic matching layer in order to improve characteristics of an ultrasonic sensor.
- the first acoustic matching layer is made of resin material and has a very large difference in expansion coefficient from a sensor housing made of inorganic material such as metal, peeling occurs at a bonding interface due to a temperature change, and deterioration of reliability characteristics of an ultrasonic sensor becomes a problem.
- the density of the first acoustic matching layer is controlled by densely filling a thermosetting material such as an epoxy resin with hollow filler such as glass balloons, and meanwhile, a ratio of resin is reduced to achieve low thermal expansion to thereby solve the bonding problem.
- a thermosetting material such as an epoxy resin
- hollow filler such as glass balloons
- the epoxy resin for obtaining the first acoustic matching layer has a density of about 1 g/cm 3 , but a density of less than 1 g/cm 3 can be obtained by dispersing a large amount of hollow filler.
- the density becomes very difficult to be achieved.
- the present disclosure provides an ultrasonic sensor that achieves both excellent sensor characteristics and durability while securing bonding properties with a first acoustic matching layer having a density exceeding 1 g/cm 3 .
- An ultrasonic sensor of the present disclosure includes: a piezoelectric element; and a plurality of acoustic matching layers including a first acoustic matching layer laminated and bonded to the piezoelectric element, in which the first acoustic matching layer includes a thermoplastic resin, and the thermoplastic resin is injected to the first acoustic matching layer from a thickness direction of the first acoustic matching layer.
- the first acoustic matching layer is made of the thermoplastic resin injected from the thickness direction of the first acoustic matching layer, a coefficient of thermal expansion is reduced in a flow direction of the resin.
- this flow direction with the longitudinal direction of the piezoelectric element and then performing bonding, stress applied to the piezoelectric element generated in a course of temperature change such as thermal shock can be reduced, and the ultrasonic sensor having excellent characteristics can be provided.
- FIG. 1 is a schematic cross-sectional view of an ultrasonic sensor according to an exemplary embodiment.
- FIG. 2 is a plan view illustrating a bonding direction of a piezoelectric element and one acoustic matching layer of the ultrasonic sensor according to the exemplary embodiment.
- FIG. 1 is a cross-sectional view of an ultrasonic sensor according to the exemplary embodiment.
- Ultrasonic sensor 1 includes piezoelectric element 7 and a plurality of acoustic matching layers including first acoustic matching layer 2 laminated and bonded to piezoelectric element 7 .
- first acoustic matching layer 2 , second acoustic matching layer 5 , and piezoelectric element 7 are provided.
- Piezoelectric element 7 is made of piezoelectric ceramics and is polarized in the thickness direction. Piezoelectric element 7 is bonded to the inside of top plate 6 a of metal housing 6 which is bottomed and has a tubular shape. Further, piezoelectric element 7 is a rectangular parallelepiped having a rectangular bonding surface with top plate 6 a.
- First acoustic matching layer 2 includes skin 3 and core 4 , and is bonded to the outer surface of top plate 6 a of metal housing 6 , and second acoustic matching layer 5 is bonded to first acoustic matching layer 2 .
- first acoustic matching layer 2 As a material suitable for first acoustic matching layer 2 in the present disclosure, a density of 1.0 g/cm 3 or more and 1.5 g/cm 3 or less is essential for matching acoustic impedance thereof with that of second acoustic matching layer 5 and reducing the internal loss. Furthermore, in order to reduce peeling of the bonding interface due to a difference in the coefficients of thermal expansion and the stress applied to piezoelectric element 7 , the flow direction of the molded resin of first acoustic matching layer 2 needs to be in parallel in bonding with the longitudinal direction (a direction in which thermal expansion is large) of piezoelectric element 7 formed in a rectangular parallelepiped.
- first acoustic matching layer 2 In order to satisfy these requirements, it is required to mold first acoustic matching layer 2 from the thickness direction and to perform bonding and fixing in a manner that the flow direction of first acoustic matching layer 2 from an injection port is parallel with the longitudinal direction of piezoelectric element 7 .
- metal housing 6 is interposed between piezoelectric element 7 and first acoustic matching layer 2 , but because the difference in the coefficients of thermal expansion between piezoelectric element 7 and metal housing 6 is substantially the same, the relationship between piezoelectric element 7 and first acoustic matching layer 2 is described including the case where metal housing 6 is not provided.
- FIG. 2 is a plan view illustrating a state in which piezoelectric element 7 and first acoustic matching layer 2 are bonded to metal housing 6 .
- First acoustic matching layer 2 includes skin 3 and core 4 as illustrated in FIG. 1 , and here, a state is illustrated in which the flow direction of the resin generated in skin 3 and indicated by arrows 9 is aligned with the longitudinal direction of piezoelectric element 7 .
- first acoustic matching layer 2 As a material of first acoustic matching layer 2 , a molding material that can create an orientation state caused by the resin flow at the time of molding is required. During this molding, the resin is injected from the thickness direction of first acoustic matching layer 2 , and a molded body having a flow direction can be obtained.
- the material include resins such as a hard urethane resin, a polyphenylene sulfide (PPS) resin, a polyoxymethylene (POM) resin, an acrylonitrile butadiene styrene (ABS) resin, a liquid crystal polymer, and a polystyrene (PS) resin.
- glass cloth or hollow filler can be mixed to enable density adjustment of the material.
- the glass cloth or the hollow filler because bonding properties with an adhesive is enhanced, strong bonding is obtained.
- the hollow filler include hollow balloons made of glass, ceramics, and resin.
- examples of a material suitable for second acoustic matching layer 5 include, in consideration of the acoustic impedance matching between the gas and the piezoelectric element, a hard resin foam that is formed of a foamed resin having a closed pore structure and has a configuration including a plurality of holes and walls adjacent thereto.
- examples of the hard resin foam include a hard acrylic foam, a hard vinyl chloride foam, a hard polypropylene foam, a hard polymethacrylimide foam, and a hard urethane foam.
- FOAMAC registered trademark
- NAVICEL registered trademark
- JFC Inc. is sold as an example of the hard vinyl chloride foam
- Zetron registered trademark
- ROHACELL registered trademark
- Daicel-Evonik Ltd. is sold as an example of the hard polymethacrylimide foam.
- the ultrasonic sensor of the present exemplary embodiment can be manufactured, for example, by the following procedure.
- metal housing 6 , piezoelectric element 7 , first acoustic matching layer 2 , and second acoustic matching layer 5 are prepared.
- First acoustic matching layer 2 and second acoustic matching layer 5 are processed in advance to have desired thicknesses.
- Piezoelectric element 7 is pasted on the inner surface of the top plate of metal housing 6 with an adhesive or the like.
- first acoustic matching layer 2 is pasted on the outer surface of the top plate, and second acoustic matching layer 5 is further pasted on first acoustic matching layer 2 .
- wiring lines 8 a and 8 b are connected to piezoelectric element 7 and metal housing 6 to complete the ultrasonic sensor.
- ultrasonic sensor 1 was prepared as follows.
- piezoelectric element 7 lead zirconate titanate having a rectangular parallelepiped shape with a thickness of 2.65 mm, a longitudinal length of 7.4 mm, and a transverse length of 3.55 mm was used. Piezoelectric element 7 has a groove in the longitudinal direction.
- an adhesive an epoxy adhesive that is liquid at room temperature and solidifies by heating was used.
- Metal housing 6 made of steel use stainless (SUS) 304 having a thickness of 0.2 mm was used.
- a polymethacrylimide foamed resin was used as second acoustic matching layer 5 . As this layer, one that has a density of 0.07 g/cm 3 and is processed into a disk shape having a dimension of 10 mm in diameter and 0.75 mm in thickness was used.
- first acoustic matching layer 2 a liquid crystal polymer obtained by mixing a hollow filler made of glass as a raw material in a low-density portion and a glass fiber in a high-density portion was used.
- a resin was injected from the thickness direction of first acoustic matching layer 2 to mold first acoustic matching layer 2 into a disk shape having a thickness of 1.0 mm and a diameter of 10 mm.
- a density of this material was 1.0 g/cm 3 .
- a resin layer filled with the hollow filler was exposed on the surface, the resin layer having a pore structure derived from the hollow filler and with a diameter of 50 ⁇ m.
- the bonding to metal housing 6 was performed after the longitudinal direction of piezoelectric element 7 was made parallel with the resin injection direction of first acoustic matching layer 2 .
- ultrasonic sensor 1 was prepared as follows.
- piezoelectric element 7 lead zirconate titanate having a rectangular parallelepiped shape with a thickness of 2.65 mm, a longitudinal length of 7.4 mm, and a transverse length of 3.55 mm was used. Piezoelectric element 7 has a groove in the longitudinal direction.
- an adhesive an epoxy adhesive that is liquid at room temperature and solidifies by heating was used.
- Metal housing 6 made of steel use stainless (SUS) 304 having a thickness of 0.2 mm was used.
- a polymethacrylimide foamed resin was used as second acoustic matching layer 5 . As this layer, one that has a density of 0.07 g/cm 3 and is processed into a disk shape having a dimension of 10 mm in diameter and 0.75 mm in thickness was used.
- first acoustic matching layer 2 a liquid crystal polymer obtained by mixing a hollow filler made of glass as a raw material in a low-density portion and a glass fiber in a high-density portion was used.
- a resin was injected from the thickness direction of first acoustic matching layer 2 to mold first acoustic matching layer 2 into a disk shape having a thickness of 1.0 mm and a diameter of 10 mm. A density of this material was 1.2 g/cm 3 .
- a resin layer filled with the hollow filler was exposed on the surface, the resin layer having a pore structure derived from the hollow filler and with a diameter of 50 ⁇ m.
- the bonding to metal housing 6 was performed after the longitudinal direction of piezoelectric element 7 was made parallel with the resin injection direction of first acoustic matching layer 2 .
- ultrasonic sensor 1 was prepared as follows.
- piezoelectric element 7 lead zirconate titanate having a rectangular parallelepiped shape with a thickness of 2.65 mm, a longitudinal length of 7.4 mm, and a transverse length of 3.55 mm was used. Piezoelectric element 7 has a groove in the longitudinal direction.
- an adhesive an epoxy adhesive that is liquid at room temperature and solidifies by heating was used.
- Metal housing 6 made of steel use stainless (SUS) 304 having a thickness of 0.2 mm was used.
- a polymethacrylimide foamed resin was used as second acoustic matching layer 5 . As this layer, one that has a density of 0.07 g/cm 3 and is processed into a disk shape having a dimension of 10 mm in diameter and 0.75 mm in thickness was used.
- first acoustic matching layer 2 a liquid crystal polymer obtained by mixing a hollow filler made of glass as a raw material in a low-density portion and a glass fiber in a high-density portion was used.
- a resin was injected from the thickness direction of first acoustic matching layer 2 to mold first acoustic matching layer 2 into a disk shape having a thickness of 1.0 mm and a diameter of 10 mm. A density of this material was 1.5 g/cm 3 .
- a resin layer filled with the hollow filler was exposed on the surface, the resin layer having a pore structure derived from the hollow filler and with a diameter of 50 ⁇ m.
- the bonding to metal housing 6 was performed after the longitudinal direction of piezoelectric element 7 was made parallel with the resin injection direction of first acoustic matching layer 2 .
- ultrasonic sensor 1 was prepared as follows.
- piezoelectric element 7 lead zirconate titanate having a rectangular parallelepiped shape with a thickness of 2.65 mm, a longitudinal length of 7.4 mm, and a transverse length of 3.55 mm was used. Piezoelectric element 7 has a groove in the longitudinal direction.
- an adhesive an epoxy adhesive that is liquid at room temperature and solidifies by heating was used.
- Metal housing 6 made of steel use stainless (SUS) 304 having a thickness of 0.2 mm was used.
- a polymethacrylimide foamed resin was used as second acoustic matching layer 5 . As this layer, one that has a density of 0.07 g/cm 3 and is processed into a disk shape having a dimension of 10 mm in diameter and 0.75 mm in thickness was used.
- first acoustic matching layer 2 a liquid crystal polymer obtained by mixing a hollow filler made of glass as a raw material in a low-density portion and a glass fiber in a high-density portion was used.
- a resin was injected from the thickness direction of first acoustic matching layer 2 to mold first acoustic matching layer 2 into a disk shape having a thickness of 1.0 mm and a diameter of 10 mm.
- a density of this material was 1.0 g/cm 3 .
- a resin layer filled with the hollow filler was exposed on the surface, the resin layer having a pore structure derived from the hollow filler and with a diameter of 50 ⁇ m.
- the bonding to metal housing 6 was performed after the resin injection direction of first acoustic matching layer 2 was rotated by 90° with respect to the longitudinal direction of piezoelectric element 7 .
- ultrasonic sensor 1 was prepared as follows.
- piezoelectric element 7 lead zirconate titanate having a rectangular parallelepiped shape with a thickness of 2.65 mm, a longitudinal length of 7.4 mm, and a transverse length of 3.55 mm was used. Piezoelectric element 7 has a groove in the longitudinal direction.
- an adhesive an epoxy adhesive that is liquid at room temperature and solidifies by heating was used.
- Metal housing 6 made of steel use stainless (SUS) 304 having a thickness of 0.2 mm was used.
- a polymethacrylimide foamed resin was used as second acoustic matching layer 5 . As this layer, one that has a density of 0.07 g/cm 3 and is processed into a disk shape having a dimension of 10 mm in diameter and 0.75 mm in thickness was used.
- first acoustic matching layer 2 a liquid crystal polymer obtained by mixing a hollow filler made of glass as a raw material in a low-density portion and a glass fiber in a high-density portion was used.
- a resin was injected from the thickness direction of first acoustic matching layer 2 to mold first acoustic matching layer 2 into a disk shape having a thickness of 1.0 mm and a diameter of 10 mm. A density of this material was 1.2 g/cm 3 .
- a resin layer filled with the hollow filler was exposed on the surface, the resin layer having a pore structure derived from the hollow filler and with a diameter of 50 ⁇ m.
- the bonding to metal housing 6 was performed after the resin injection direction of first acoustic matching layer 2 was rotated by 90° with respect to the longitudinal direction of piezoelectric element 7 .
- ultrasonic sensor 1 was prepared as follows.
- piezoelectric element 7 lead zirconate titanate having a rectangular parallelepiped shape with a thickness of 2.65 mm, a longitudinal length of 7.4 mm, and a transverse length of 3.55 mm was used. Piezoelectric element 7 has a groove in the longitudinal direction.
- an adhesive an epoxy adhesive that is liquid at room temperature and solidifies by heating was used.
- Metal housing 6 made of steel use stainless (SUS) 304 having a thickness of 0.2 mm was used.
- a polymethacrylimide foamed resin was used as second acoustic matching layer 5 . As this layer, one that has a density of 0.07 g/cm 3 and is processed into a disk shape having a dimension of 10 mm in diameter and 0.75 mm in thickness was used.
- first acoustic matching layer 2 a liquid crystal polymer obtained by mixing a hollow filler made of glass as a raw material in a low-density portion and a glass fiber in a high-density portion was used.
- a resin was injected from the thickness direction of first acoustic matching layer 2 to mold first acoustic matching layer 2 into a disk shape having a thickness of 1.0 mm and a diameter of 10 mm. A density of this material was 1.5 g/cm 3 .
- a resin layer filled with the hollow filler was exposed on the surface, the resin layer having a pore structure derived from the hollow filler and with a diameter of 50 ⁇ m.
- the bonding to metal housing 6 was performed after the resin injection direction of first acoustic matching layer 2 was rotated by 90° with respect to the longitudinal direction of piezoelectric element 7 .
- ultrasonic sensor 1 was prepared as follows.
- piezoelectric element 7 lead zirconate titanate having a rectangular parallelepiped shape with a thickness of 2.65 mm, a longitudinal length of 7.4 mm, and a transverse length of 3.55 mm was used. Piezoelectric element 7 has a groove in the longitudinal direction.
- an adhesive an epoxy adhesive that is liquid at room temperature and solidifies by heating was used.
- Metal housing 6 made of steel use stainless (SUS) 304 having a thickness of 0.2 mm was used.
- a polymethacrylimide foamed resin was used as second acoustic matching layer 5 . As this layer, one that has a density of 0.07 g/cm 3 and is processed into a disk shape having a dimension of 10 mm in diameter and 0.75 mm in thickness was used.
- a glass balloon-filled epoxy resin which is an epoxy resin filled with hollow filler made of glass as a raw material was used.
- the density of this material was 0.5 g/cm 3 , and the material was processed into a disk shape having a thickness of 1.0 mm and a diameter of 10 mm and used. Note that the material has, on the surface, a pore structure derived from the hollow filler and with a diameter of 50 ⁇ m.
- the characteristics of each of the prepared ultrasonic sensors 1 were measured.
- the pair of prepared ultrasonic sensors 1 were opposed to each other, and ultrasonic waves were transmitted and received using one of the pair as a transmitter and the other as a receiver. Relative values with respect to the characteristics of the comparative example, which is set to 1, are shown.
- the sensor was subjected to 200 cycles of a thermal shock test in which the environment of ⁇ 40° C. for 30 minutes and the environment of 80° C. for 30 minutes were set as 1 cycle, the characteristics of the sensor after the test were compared with the initial characteristics of the sensor, and a rate of change thereof was confirmed.
- the sample in which the density of first acoustic matching layer 2 is in the range of 1.0 g/cm 3 to 1.5 g/cm 3 exhibits high characteristics. This is considered to be because, from the viewpoint of the impedance matching of piezoelectric element 7 and second acoustic matching layer 5 and the transmission efficiency of the ultrasonic waves in first acoustic matching layer 2 , the sensor is in an appropriate range regarding hardness and impedance matching. In particular, in the case where the density of first acoustic matching layer 2 is 1.5 g/cm 3 , high characteristics are exhibited.
- an ultrasonic sensor includes: a piezoelectric element; and a plurality of acoustic matching layers including a first acoustic matching layer laminated and bonded to the piezoelectric element, in which the first acoustic matching layer includes a thermoplastic resin, and the thermoplastic resin is injected to the first acoustic matching layer from a thickness direction of the first acoustic matching layer.
- the piezoelectric element may be a rectangular parallelepiped having a rectangular bonding surface
- the first acoustic matching layer may have a flow direction caused by injection of the thermoplastic resin, and the flow direction may be matched in parallel with a longitudinal direction of the piezoelectric element before laminating and bonding are performed.
- the first acoustic matching layer may have an average density of 1.0 g/cm 3 or more and 1.5 g/cm 3 or less.
- the ultrasonic waves can be transmitted with high efficiency from the piezoelectric element to the acoustic matching layer bonded to the first acoustic matching layer, so that the characteristics of the ultrasonic sensor are improved.
- the first acoustic matching layer may have an average density of 1.0 g/cm 3 or more and 1.5 g/cm 3 or less.
- the ultrasonic waves can be transmitted with high efficiency from the piezoelectric element to the acoustic matching layer bonded to the first acoustic matching layer, so that the characteristics of the ultrasonic sensor are improved.
- the first acoustic matching layer may include, as a constituent component, a material filled with hollow spheres made of glass, ceramic, or resin. Because the hollow spheres have a very low density and become voids when appearing on the surface by polishing, cutting, or the like, an anchor effect can be easily obtained at the time of bonding.
- the first acoustic matching layer may have a thickness set to approximately 1 ⁇ 4 of the speed of sound.
- the first acoustic matching layer may have a thickness set to approximately 1 ⁇ 4 of the speed of sound.
- the ultrasonic sensor of the present disclosure is suitable for use in flow rate meters for measuring various fluids.
- the sensor is suitably used for applications requiring excellent durability in use environments such as high temperature and low temperature.
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- General Physics & Mathematics (AREA)
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- Acoustics & Sound (AREA)
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- Transducers For Ultrasonic Waves (AREA)
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Abstract
Description
Z22 =Z1×Z3 (1)
is satisfied.
Z22 =Z1×Z3, and
Z32 =Z2×Z4
is satisfied.
- PTL 1: Unexamined Japanese Patent Publication No. 2018-61209
TABLE 1 | |||||||
Comparative | Comparative | Comparative | Comparative | ||||
Example 1 | Example 2 | Example 3 | example 1 | example 2 | example 3 | example 4 | |
First acoustic matching | Liquid | Liquid | Liquid | Liquid | Liquid | Liquid | Epoxy |
layer | crystal | crystal | crystal | crystal | crystal | crystal | |
polymer | polymer | polymer | polymer | polymer | polymer | ||
Density (g/cm3) | 1.0 | 1.2 | 1.5 | 1.0 | 1.2 | 1.5 | 0.5 |
Flow direction and | Parallel | Parallel | Parallel | 90° | 90° | 90° | No |
(longitudinal) direction of | directivity | ||||||
piezoelectric element | |||||||
Second acoustic matching | Foamed | Foamed | Foamed | Foamed | Foamed | Foamedr | Foamed |
layer | resin | resin | resin | resin | resin | esin | resin |
Characteristics of | 1.8 | 2.0 | 2.3 | 1.8 | 2.0 | 2.3 | 1 |
ultrasonic sensor | |||||||
Reliability | Very good | Very good | Very good | No good | No good | No good | Good |
-
- 1 ultrasonic sensor
- 2 first acoustic matching layer
- 3 skin
- 4 core
- 5 second acoustic matching layer
- 6 metal housing
- 7 piezoelectric element
Claims (5)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2019145885A JP7296581B2 (en) | 2019-08-08 | 2019-08-08 | ultrasonic sensor |
JP2019-145885 | 2019-08-08 | ||
PCT/JP2020/028212 WO2021024790A1 (en) | 2019-08-08 | 2020-07-21 | Ultrasonic sensor |
Publications (2)
Publication Number | Publication Date |
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US20220163378A1 US20220163378A1 (en) | 2022-05-26 |
US11874159B2 true US11874159B2 (en) | 2024-01-16 |
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ID=74504103
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US17/616,985 Active 2040-09-01 US11874159B2 (en) | 2019-08-08 | 2020-07-21 | Ultrasonic sensor |
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Country | Link |
---|---|
US (1) | US11874159B2 (en) |
EP (1) | EP4013068A4 (en) |
JP (1) | JP7296581B2 (en) |
CN (1) | CN114208211B (en) |
WO (1) | WO2021024790A1 (en) |
Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2002058099A (en) | 2000-08-11 | 2002-02-22 | Murata Mfg Co Ltd | Method for producing acoustic matching layer, acoustic matching layer produced by the method, ultrasonic sensor comprising the layer, and electronic apparatus using the layer |
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JP2011077572A (en) * | 2009-09-29 | 2011-04-14 | Fujifilm Corp | Ultrasonic transducer and producing method thereof, and ultrasonic probe |
JP5950860B2 (en) | 2013-04-09 | 2016-07-13 | 三菱電機株式会社 | Aerial ultrasonic sensor |
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WO2021024790A1 (en) | 2021-02-11 |
CN114208211B (en) | 2024-05-28 |
EP4013068A1 (en) | 2022-06-15 |
JP2021027532A (en) | 2021-02-22 |
EP4013068A4 (en) | 2022-08-31 |
CN114208211A (en) | 2022-03-18 |
JP7296581B2 (en) | 2023-06-23 |
US20220163378A1 (en) | 2022-05-26 |
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